Asking what the oldest living thing is on Earth seems like a simple question, but it opens up into several branches depending on the how you define a living organism and in what state the organism exists. Speaking of branches, most of the organisms listed as the oldest are plants – trees or shrubs. Technically, however, the oldest living organisms on Earth are bacteria. Some species of bacteria have an ability to form a protective shield around themselves called a spore. When they form the spore, the bacteria go into a type of hibernation called suspended animation. When conditions outside are optimal for survival, the spore disintegrates and the bacteria become active again. Deep in a mine in Carlsbad, NM, scientists have discovered Bacillus bacteria stuck in salt crystals. When they freed the bacteria, they became active. It is estimated that the bacteria were caught in the salt crystals about 250 million years ago, making those bacteria the oldest living organisms. The thing is, is that once they become active, they really don’t live very long.

A lot of controversy surrounds what, exactly, is the oldest, continuously active, individual organism on the planet. The organism most agreed upon is a bristlecone pine tree in the White mountains of California. One tree there, named Methuselah, is 4,775 years old. Its identity is kept a secret to protect it from vandalism. It does have several other brothers, however, all around 4,000 years old.

Recently, scientists have claimed to find a couple of other organisms that are older than Methuselah. A shrub in the Mojave Desert called the creosote bush has been discovered that is extremely long-lived. The oldest creosote bush found so far is about 11,700 years old. Also, on the border of Norway and Sweden, a Norway spruce is said to have been discovered that is 8,000 years old but they were dated using the carbon dating method and many scientists don’t believe it is as accurate as the ring-counting method used on Methuselah.

In another category, the Quaking Aspen may be the oldest, multi-organism. The Quaking Aspen has an underground root structure that branches upward to form a colony of trees. The Pando colony in Utah has a root system that is about 80,000 years old.